Philips TDA1072A Datasheet

INTEGRATED CIRCUITS

TDA1072A

AM receiver circuit

Product specification			May 1984
File under Integrated Circuits, IC01

Philips Semiconductors	Product specification
AM receiver circuit	TDA1072A

GENERAL DESCRIPTION

The TDA1072A integrated AM receiver circuit performs the active and part of the filtering functions of an AM radio receiver. It is intended for use in mains-fed home receivers and car radios. The circuit can be used for oscillator frequencies up to 50 MHz and can handle r.f. signals up to 500 mV. R.F. radiation and sensitivity to interference are minimized by an almost symmetrical design. The voltage-controlled oscillator provides signals with extremely low distortion and high spectral purity over the whole frequency range even when tuning with variable capacitance diodes. If required, band switching diodes can easily be applied. Selectivity is obtained using a block filter before the i.f. amplifier.

Features

∙Inputs protected against damage by static discharge

∙Gain-controlled r.f. stage

∙Double balanced mixer

∙Separately buffered, voltage-controlled and temperature-compensated oscillator, designed for simple coils

∙Gain-controlled i.f. stage with wide a.g.c. range

∙Full-wave, balanced envelope detector

∙Internal generation of a.g.c. voltage with possibility of second-order filtering

∙Buffered field strength indicator driver with short-circuit protection

∙A.F. preamplifier with possibilities for simple a.f. filtering

∙Electronic standby switch.

QUICK REFERENCE DATA

Supply voltage range	VP	7,5 to 18		V
Supply current range	IP		15 to 30	mA
R.F. input voltage for S + N/N = 6 dB at m = 30%	Vi	typ.	1,5	μV
R.F. input voltage for 3% total harmonic
distortion (THD) at m = 80%	Vi	typ.	500	mV
A.F. output voltage with Vi = 2 mV;
fi = 1 MHz; m = 30% and fm = 400 Hz	Vo(af)	typ.	310	mV
A.G.C. range: change of Vi for 1 dB change of Vo(af)		typ.	86	dB
Field strength indicator voltage at
Vi = 500 mV; RL(9) = 2,7 kΩ	VIND	typ.	2,8	V

PACKAGE OUTLINE

16-lead DIL; plastic (SOT38); SOT38-1; 1996 August 09.

May 1984

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Philips Semiconductors	Product specification
AM receiver circuit	TDA1072A

(1)Coil data: TOKO sample no. 7XNS-A7523DY; L1 : N1/N2 = 12/32; Qo = 65; QB = 57. Filter data: ZF = 700 Ω at R3-4 = 3 kΩ; ZI = 4,8 kΩ.

Fig.1 Block diagram and test circuit (connections shown in broken lines are not part of the test circuit).

May 1984

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Philips Semiconductors	Product specification
AM receiver circuit	TDA1072A

FUNCTIONAL DESCRIPTION

Gain-controlled r.f. stage and mixer

The differential amplifier in the r.f. stage employs an a.g.c. negative feedback network to provide a wide dynamic range. Very good cross-modulation behaviour is achieved by a.g.c. delays at the various signal stages. Large signals are handled with low distortion and the S/N ratio of small signals is improved. Low noise working is achieved in the differential amplifier by using transistors with low base resistance.

A double balanced mixer provides the i.f. output signal to pin 1.

Oscillator

The differential amplifier oscillator is temperature compensated and is suitable for simple coil connection. The oscillator is voltage-controlled and has little distortion or spurious radiation. It is specially suitable for electronic tuning using variable capacitance diodes. Band switching diodes can easily be applied using the stabilized voltage V11-16. An extra buffered oscillator output (pin 10) is available for driving a synthesizer. If this is not needed, resistor RL(10) can be omitted.

Gain-controlled i.f. amplifier

This amplifier comprises two cascaded, variable-gain differential amplifier stages coupled by a band-pass filter. Both stages are gain-controlled by the a.g.c. negative feedback network.

Detector

The full-wave, balanced envelope detector has very low distortion over a wide dynamic range. Residual i.f. carrier is blocked from the signal path by an internal low-pass filter.

A.F. preamplifier

This stage preamplifies the audio frequency output signal. The amplifier output has an emitter follower with a series resistor which, together with an external capacitor, yields the required low-pass for a.f. filtering.

A.G.C. amplifier

The a.g.c. amplifier provides a control voltage which is proportional to the carrier amplitude. Second-order filtering of the a.g.c. voltage achieves signals with very little distortion, even at low audio frequencies. This method of filtering also gives fast a.g.c. settling time which is advantageous for electronic search tuning. The a.g.c. settling time can be further reduced by using capacitors of smaller value in the external filter (C16 and C17). The a.g.c. voltage is fed to the r.f. and i.f. stages via suitable a.g.c. delays. The capacitor at pin 7 can be omitted for low-cost applications.

Field strength indicator output

A buffered voltage source provides a high-level field strength output signal which has good linearity for logarithmic input signals over the whole dynamic range. If the field strength information is not needed, RL(9) can be omitted.

Standby switch

This switch is primarily intended for AM/FM band switching. During standby mode the oscillator, mixer and a.f. preamplifier are switched off.

Short-circuit protection

All pins have short-circuit protection to ground.

May 1984

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Philips Semiconductors		Product specification
AM receiver circuit		TDA1072A
RATINGS
Limiting values in accordance with the Absolute Maximum Rating System (IEC 134)
Supply voltage	VP = V13-16	max.	20	V
Total power dissipation	Ptot	max.	875 mW
Input voltage	ïV14-15ï	max.	12	V
	-V14-16, -V15-16	max.	0,6	V
	V14-16, V15-16	max.	VP	V
Input current	ïI14ï, ïI15ï	max.	200	mA
Operating ambient temperature range	Tamb	-40 to	+ 80	°C
Storage temperature range	Tstg	-55 to	+ 150	°C
Junction temperature	Tj	max.	+ 125	°C
THERMAL RESISTANCE
From junction to ambient	Rth j-a	=	80	K/W

DEVICE CHARACTERISTICS

VP = V13-16 = 8,5 V; Tamb = 25 °C; fi = 1 MHz; fm = 400 Hz; m = 30%; fif = 460 kHz; measured in test circuit of Fig.1; unless otherwise specified

PARAMETER	SYMBOL	MIN.	TYP.	MAX.	UNIT
Supplies
Supply voltage	VP = V13-16	7,5	8,5	18	V
Supply current	IP = I13	15	23	30	mA
R.F. stage and mixer
Input voltage (d.c. value)	V14-16, V15-16	-	VP/2	-	V
R.F. input impedance at Vi < 300 mV	R14-16, R15-16	-	5,5	-	kW
	C14-16, C15-16	-	25	-	pF
R.F. input impedance at Vi > 10 mV	R14-16, R15-16	-	8	-	kW
	C14-16, C15-16	-	22	-	pF
I.F. output impedance	R1-16	500	-	-	kW
	C1-16	-	6	-	pF
Conversion transconductance
before start of a.g.c.	I1/Vi	-	6,5	-	mA/V
Maximum i.f. output voltage, inductive
coupling to pin 1	V1-13(p-p)	-	5	-	V
D.C. value of output current (pin 1)
at Vi = 0 V	I1	-	1,2	-	mA
A.G.C. range of input stage		-	30	-	dB
R.F. signal handling capability:
input voltage for THD = 3% at m = 80%	Vi(rms)	-	500	-	mV

May 1984

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Philips Semiconductors			Product specification
AM receiver circuit				TDA1072A
PARAMETER	SYMBOL	MIN.	TYP.		MAX.	UNIT
Oscillator
Frequency range	fosc	0,6	-		60	MHz
Oscillator amplitude (pins 11 to 12)	V11-12	-	130		150	mV
External load impedance	R12-11(ext)	0,5	-		200	kW
External load impedance for no oscillation	R12-11(ext)	-	-		60	W
Ripple rejection at VP(rms) = 100 mV;
fP = 100 Hz
(RR = 20 log [V13-16/V11-16])	RR	-	55		-	dB
Source voltage for switching diodes (6 ´ VBE)	V11-16	-	4,2		-	V
D.C. output current (for switching diodes)	-I11	0	-		20	mA
Change of output voltage at
DI11 = 20 mA (switch to maximum load)	DV11-16	-	0,5		-	V
Buffered oscillator output
D.C. output voltage	V10-16	-	0,7		-	V
Output signal amplitude	V10-16(p-p)	-	320		-	mV
Output impedance	R10	-	170		-	W
Output current	-I10(peak)	-	-		3	mA
I.F., a.g.c. and a.f. stages
D.C. input voltage	V3-16, V4-16	-	2,0		-	V
I.F. input impedance	R3-4	2,4	3		3,9	kW
	C3-4	-	7		-	pF
I.F. input voltage for
THD = 3% at m = 80%	V3-4	-	90		-	mV
Voltage gain before start of a.g.c.	V3-4/V6-16	-	68		-	dB
A.G.C. range of i.f. stages: change of
V3-4 for 1 dB change of Vo(af);
V3-4(ref) = 75 mV	DV3-4	-	55		-	dB
A.F. output voltage at V3-4(if) = 50 mV	Vo(af)	-	130		-	mV
A.F. output voltage at V3-4(if) = 1 mV	Vo(af)	-	310		-	mV
A.F. output impedance (pin 6)	ïZoï	-	3,5		-	kW
Indicator driver
Output voltage at Vi = 0 mV;
RL(9) = 2,7 kW	V9-16	-	20		150	mV
Output voltage at Vi = 500 mV;
RL(9) = 2,7 kW	V9-16	2,5	2,8		3,1	V
Load resistance	RL(9)	1,5	-		-	kW

May 1984

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